Tool with linear drive mechanism

ABSTRACT

A hand tool with a mechanical linear drive mechanism coupled to a linear activated working implement. The drive mechanism includes a geared planetary roller screw that includes a torque tube connected to a roller screw&#39;s nut body. The planetary roller screw includes a fixed outer race, a rotating set of grooved rollers axially aligned inside the outer race, a cylindrical nut body located inside the set of grooved roller, a plurality of inner rollers axially aligned and inside the nut body, a threaded shaft axially aligned and inside the inner rollers, and a torque tube axially aligned inside the inner rollers. The torque tube is connected at one end to a gear box which is coupled to an electric motor. When the electric motor is activated, the torque tube is rotated which causes a threaded shaft in the tool to move axially. A working implement is coupled to the distal end of the threaded shaft.

TECHNICAL FIELD

This invention relates to linear drive mechanisms, and more particularlyto linear drive mechanism that are portable and compact.

BACKGROUND ART

Portable hand tools are commonly used by emergency personnel to bend,spread or cut metal pieces to free drivers and passengers from theirvehicles after accidents. The working implements on these hand tools areactuated by a linear mechanism coupled to a hydraulic cylinder. Thehydraulic cylinder is coupled to a gas or electricity powered hydraulicpump.

One drawback with power hand tools that use hydraulic pumps is thehydraulic pump's periodic inspection and maintenance requirements.Another drawback is the tool's housing is elongated to accommodate thehydraulic pump, the linear mechanism and the working implement.

What is needed is a portable hand tool with an electric, non-hydrauliclinear drive mechanism coupled to a working implement.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a portable hand toolwith a lightweight, compact linear drive mechanism that uses a rollerscrew coupled to the tool's working implement.

The linear drive mechanism includes a roller screw threaded shaft withan external nut and rollers mounted over an axially aligned threadedshaft longitudinally aligned inside the tool's elongated body. In oneembodiment, the proximal end of the threaded shaft is coupled to agearbox that is coupled to an electric motor that can be operated inboth forward and reverse directions. The gearbox includes a plurality ofgears configured to reduce the RPM output from the electric motor. Inthe first embodiment, the gearbox is also coupled to a frictional clutchconfigured to engage the inside surface of the roller screw shaft whenrotated a specific amount. In a second embodiment, the frictional clutchis eliminated and replaced by a multiple stage gear box.

When the electric motor is activated, the frictional clutch or multiplestage gear box causes the threaded shaft to rotate. In the firstembodiment, as the threaded shaft is rotated, the roller screw's nutbody moves longitudinally inside the tool's elongated body. In thesecond embodiment, the nut body is fixed axially inside the tool's outerhousing so as the nut body is rotated, the threaded shaft moves axiallyinside the tool's outer housing.

Mounted distally inside the elongated body and adjacent to the distalend of the roller nut is a tool implement coupler that attaches to atool implement that extends from tool's distal end. The tool implementmay include two pivoting cutting jaws, two pivoting spreader jaws, or aram bar. A rechargeable battery s attached to the proximal end of theelongated housing to energize the electric motor.

In the second embodiment, the mechanical linear drive is a gearedplanetary roller screw that includes a torque tube connected to a rollerscrew's nut body. The planetary roller screw includes a fixed outerrace, a rotating set of grooved rollers axially aligned inside the outerrace, a cylindrical nut body located inside the set of grooved rollers,a plurality of threaded inner rollers axially aligned and inside the nutbody, a threaded shaft axially aligned and inside the inner rollers, anda torque tube fixed to the nut body. The nut body operates as an innerrace for the grooved inner rollers. The torque tube is connected at oneend to the gear box coupled to an electric motor. When electric motor isactivated, the torque tube is rotated which causes a threaded shaft inthe tool to move axially inside the tool. A working implement is coupledto the distal end of the threaded shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side elevational view of a first embodiment of atool with two cutting jaws, a frictional clutch, and a linear drivemechanism.

FIG. 2 is a side elevational view of a second embodiment of a tool withtwo cutting jaws and a geared planetary roller screw used as a lineardrive mechanism.

FIG. 3 is a sectional side elevational view of the tool shown in FIG. 2.

FIG. 4 is an enlarged, partial sectional side elevational view of thegeared planetary roller screw located inside the tool shown in FIGS. 2and 3.

FIG. 5 is an end sectional view taken along line 5-5 in FIG. 3.

FIG. 6 is an end sectional view taken along line 6-6 in FIG. 3.

FIG. 7 is an end sectional view taken along line 7-7 in FIG. 3.

FIG. 8 is an end sectional view taken along line 8-8 in FIG. 3.

FIG. 9 is an end sectional view taken along line 9-9 in FIG. 3.

FIG. 10 is an exploded view of the dowel pin, the outer race, thegrooved roller located inside the outer race, the snap ring, the nutbody located inside the grooved roller, the inner threaded roller, ringgear, the wiper seal, and the threaded shaft.

FIG. 11 is a side elevational view of a tool with two spreader jaws.

FIG. 12 is a side elevation view of the tool shown in FIG. 11 with thefront section of the outer housing removed to show the linkage armscoupled to the spreader arms.

FIG. 13 is a side elevational view of a tool with a ram bar extendinglongitudinally from the front section.

BEST MODE FOR CARRYING OUT THE INVENTION

A tool 10 with a lightweight linear drive mechanism 12 in the tool'selongated body 15 and designed to provide 70,000 to 120,000 lbs of forceto the tool's working implement 70. FIG. 1 discloses a first embodimentof the tool 10 that includes a roller screw assembly shown and describedin U.S. Pat. No. 7,044,017 and incorporated herein. The roller screwassembly includes a roller screw shaft 22 and a nut body 50 mounted overthe outer surface of the roller screw shaft 22. Disposed inside the nutbody 50 is a plurality of longitudinally aligned rollers 54 designed toremain in constant contact with formed helical threads 23 on the outersurface of the roller screw shaft 22 and with grooves 51 formed on theinterior surface of the nut body 50 during operation. The rollers 54,however, can shift axially and re-positioned with respect to both thenut body 50 and the roller screw shaft 22 as the roller screw shaft 22is rotated while remaining in rolling contact with the nut body 50.

The grooves 51 on the nut body 50 are helical over most of the insidesurface of the nut body 50. Over a small region of the inside surface ofthe center bore, hereinafter referred to as the cross-over region, thegrooves 51 extend radically outward and axially. Located inside the nutbody 50 is a plurality of longitudinally aligned rollers 54. Formed overthe outer surface of the rollers 54 are non-helical grooves 55 that meshwith a plurality of closed, partially helical grooves 51 on the nut body50 and with the helical threads 23 on the roller screw shaft 22 thatextends through the nut body 50. When the rollers 54 travel through thecross-over region, two compression rings on the opposite ends of therollers 54 force the rollers 54 radially outward so they maintainengagement with the grooves 51 on the nut body 50.

Because the grooves 51 in the cross-over region extend axially, therollers 54 are shifted axially regarding the nut body 50 and rollerscrew shaft 22 when centrally disposed in the cross-over region. As therollers 54 leave the cross-over region, they are extended axially andreturned to the original starting point of the grooves 51 on the nutbody 50.

The grooves 55 on the rollers 54 are non-helical and designed to engageboth the closed grooves 51 on the nut body 50 and on the helical threads23 on the roller screw shaft 22. The diameters of the roller screw shaft22, the nut body 50, and rollers 54 are sufficient in size so that whenthe grooves 55 on the rollers 54 engage the grooves 51 on the nut body50 in the cross-over region, they progressively disengage from thehelical threads 23 on the shaft 22 enabling the rollers 54 to moveaxially with respect to the nut body 50. As the rollers 54 leave thecross-over region, they travel axially and re-engage the helical threads23 on the roller screw shaft 22. With each rotation of the roller screwshaft 22 inside the nut body 50, the rollers 54 are in constant rollingcontact with the grooves 51 on the nut body 50.

The above described roller screw assembly 12 is longitudinally alignedinside the hollow cavity 18 formed in the hand tool's elongated body 15.The roller screw shaft 22 is coaxially aligned inside the cavity 18 andincludes a longitudinally aligned cavity 24. Mounted inside the cavity24 and adjacent to the proximal end of the roller screw shaft 22 is anelectric motor 30. Mounted adjacent to the electric motor 30 and insidethe cavity 24 is a gearbox 36. The gearbox 36 is coupled to the driveshaft on the electric motor 30 and configured to reduce the RPM outputfrom the electric motor 30.

The opposite end of the gearbox 36 is coupled to a frictional clutch 40also located inside the distal end of the cavity 24. When the electricmotor 30 is activated, the gear box 36 causes the frictional clutch 40to rotate that eventually engages the exposed section of the insidesurface of the roller screw shaft 22 and causing the roller screw shaft22 to rotate inside the nut body 50.

Longitudinally aligned and located distally inside the elongated body 15is an elongated push cap 60. The push cap 60 includes a wide proximalsection and a narrow front neck section. The distal end of the rollerscrew shaft 22 extends into the center bore formed in the push cap 60.When assembled, the end surface of the proximal section abuts the distalend surface of the nut body 50. When roller screw shaft 22 is rotated,the nut body 50 travels longitudinally inside the elongated body 15 in afore or aft direction depending on the direction of rotation of theelectric motor 30.

Mounted on the distal end of the push cap 60 is a pivot pin 65 coupledto toggle linkage 68. The toggle linkage 68 is connected to one or morecutter or spreader blades 70 used on the working implement.

The roller screw shaft 22 is held coaxially inside the elongated body 15and the push cap 60 by bearings 85. The roller screw shaft 22 includes aperpendicular aligned base that fits inside the proximal wide endsection of the elongated body 15. The electric motor 30 is held insidethe proximal end of the roller screw shaft 22 by a transverse memberthat extends across the proximal end opening. The electric motor 30includes a secondary shaft coupled to an electrical brake mounted on theproximal end of the elongated body 15.

A rechargeable battery 90 may be attached to the proximal end of theelongated body 15 to energize the electric motor 30.

FIGS. 2-10 show a second embodiment of the tool 200 with a lightweightlinear drive mechanism that uses an electric motor assembly 205 coupledto a multiple stage gear box 220 used in place of the frictional clutch40. Coupled to the gear box 220 is a geared planetary roller screw 250that is used in place of the roller screw assembly described above. Thegeared planetary roller screw 250 is similar to the roller screw shownin U.S. Pat. No. 2,683,379 (Strandgren) which is now incorporatedherein.

As shown in FIG. 4, the geared planetary roller screw 250 includes afixed cylindrical, fixed outer race 260 axially aligned inside thetool's outer housing 210. The outer race 260 includes a plurality ofinternal, non-helical grooves 264. A dowel pin 268 is inserted inbetween the outer housing 210 and the outer race 260 to hold the outerrace 260 inside the tool 200. A set screw 270 is used to retain thedowel pin 268 in the outer housing 210.

Located adjacent inside the outer race 260 is a plurality of outergrooved rollers 275. Formed on each end of the outer grooved rollers 275are axially aligned axles 278 that engage bores formed on two spacerrings 280 coaxially aligned inside the outer housing 210. Each groovedroller 275 includes a plurality of non-helical grooves 282 configured tomesh with the non-helical grooves 264 formed on the outer race 260.During operation, the set of grooved rollers 275 and the two spacerrings 280 rotate inside the outer housing 210.

Located adjacent and inside the grooved rollers 275 is a cylindrical nutbody 288 configured to rotate inside the outer housing 210. The nut body288 includes a plurality of external non-helical threads 290 that meshwith the non-helical grooves 282 on the grooved rollers 275. The nutbody 288 acts as an inner race for the outer groove rollers 275. The nutbody 288 also includes a plurality of internal helical threads 292. Thenon-helical threads 290 on the external surface of the nut body 288allow the nut body 288 to rotated but prevent the nut body 288 frommoving axially inside the outer housing 210.

Located adjacent and inside the nut body 288 is a plurality of axiallyaligned inner rollers 300. Each inner roller 300 includes externalhelical threads 304 that mesh with the internal helical threads 292 onthe inside surface of the nut body 288. Each inner roller 300 includesat its opposite ends a set gear teeth 306 that engage two ring gears 305aligned transversely inside the outer housing 210. Formed on the tworing gears 305 are a plurality of external teeth 306 that mesh with thegear teeth 302 on opposite ends of the inner rollers 300. Duringoperation the inner rollers 300 individually rotate on theirlongitudinally axis and rotate around a threaded shaft 310 that extendscoaxially and inside the outer housing 210.

The threaded shaft 310 includes a plurality of helical external threads314 that extend substantially the entire length and mesh with thehelical threads 304 on the inner rollers 300. In the embodiment shownherein, the threaded shaft 310 is approximately twice as long as theinner rollers 300. The threaded shaft 310 is hollow with a proximal endand a distal end. Attached to the distal end is a combination endcap/clevis 320.

Disposed inside the outer housing 210 is a torque tube 330 that includesa narrow cylindrical hollow neck 334 and a wide cylindrical body 338.The neck 334 is configured to surround the rear portion of the threadedshaft 310 that extends rearward from the inner rollers 300. The widecylindrical body 338 is configured to extend outward and partiallyextend around the exterior surface of the nut body 288. Formed theinside surface of the wide cylindrical body 338 and the adjacent surfaceof the nut body 288 is keyway. A complementary key 340 is inserted intothe two keyways to affix the torque tube 330 to the nut body 288. Formedon the proximal end of the torque tube 330 are one or more receivingbores that receive pegs 222 that extend longitudinally inward from thegear box 220.

During operation, the electric motor 205 is activated which causes thepegs 222 on the gear box 220 to rotate. The rotation of the pegs 222 onthe gear box 220 causes the torque tube 330 to rotate which causes thenut body 288 to rotate. Because the grooved rollers 275 prevent the nutbody 288 from moving longitudinally inside the outer housing 210, theinner rollers 300 engage the threads 304 on the threaded shaft 310causing the threaded shaft 310 to move longitudinally inside the outerhousing 210.

FIGS. 2 and 3 show the tool 200 attached to a tool implement 350 withtwo cutting jaws 360, 380 extending from the distal end of the outerhousing 210. The two cutting jaws 360, 380 include cutting blade edges366, 386 and middle sections 365, 385, respectively, rotatingly coupledtogether by a rigid front pin 390. The rear section 361, 381 of eachjaws 360, 380, respectively, is pivotally connected to a linkage arm353, 355, respectively. The rear end of each linkage arm 353, 355 isconnected to a combination end cap/clevis 320 (shown in FIG. 4) which isconnected to the end cap 320. The front end of each linkage arm 353, 355is connected to a cutting jaws 360, 380 via pins 362, 382, respectively.During use, the threaded shaft 310 moves axially inside the outerhousing 210 causing the rear sections 361, 381 of the two jaws 360, 380,respectively, to move towards or away from the front pin 390 and therebyopening and closing the jaws 360, 380.

FIGS. 11 and 12 are side elevational views of a tool implement 400 withtwo spreader jaws 410, 420 that extend from the distal end of the outertool housing 212. The spreader jaws 410, 420 are connected to linkagearms 353, 355 and operate in a manner that enable the spreader arms 410,420 to open and close.

FIG. 13 is a side elevational view of a tool implement 500 with a rambar 510 extending longitudinally from the distal end of the toolhousing. The ram bar 510 is connected directly to the distal end of theend cap or to the threaded shaft.

INDUSTRIAL APPLICABILITY

This invention has application in the portable hand tool and emergencyequipment industries, and more particularly in such industries that needtools and equipment to covert rotation movement from an electric motorto a linear activated tool implement.

We claim:
 1. A tool with a linear actuated working implement,comprising, a. an outer housing with a front end; b. a geared planetaryroller screw disposed inside said outer housing, said roller screwincludes: a fixed outer race axially aligned inside said outer housing,said outer race includes a plurality of internal non-helical grooves; aplurality of axially aligned grooved rollers radially aligned over theinside surface of said outer race and rotated as a set around said outerrace, each said grooved roller includes external non-helical groovesthat mesh with said non-helical grooves on said outer race; acylindrical nut body axially aligned with and located inside saidgrooved rollers, said nut body includes a plurality of externalnon-helical threads that mesh with said non-helical grooves on saidgrooved rollers, said nut body includes a plurality of internal helicalthreads, said nut body configured to rotate inside said outer housingand not move longitudinally inside said outer housing; a plurality ofinner rollers axially aligned and located inside said nut body, eachsaid inner roller includes external helical threads that mesh with saidinternal helical threads on said nut body, each said inner rollerincludes a set gear teeth located at each end that engage two ring gearsaligned transversely inside said outer housing with a plurality of teeththat mesh with said gear teeth on said inner rollers; a threaded shaftaxially aligned with said outer race, said threaded shaft includes aplurality of helical external threads that mesh with said helicalthreads on said inner rollers, said threaded shaft includes a proximalend and a distal end; a torque tube axially aligned with said outerrace, said torque tube includes a narrow neck coaxially aligned aroundsaid proximal end of said threaded shaft and a wide body that at leastpartially extends around and coupled to said nut body, whereby when saidtorque tube is rotated, said nut body rotates inside said groovedrollers causing said grooved rollers to individually rotate around saidthreaded shaft causing said threaded shaft to move axially with respectto said nut body; c. an electric motor; d. a gearbox disposed betweensaid torque tube and said electric motor and configured to adjust theRPM output from the electric motor; e. a tool implement linkage coupledto said distal end of said threaded shaft; f. a linear activated toolimplement coupled to said tool implement linkage extending from saidfront end of said outer housing; and, g. an electricity source connectedto said electric motor.
 2. The tool, as recited in claim 1, wherein saidtool implement is a pair of cutting implements extending from said outerhousing, said cutting implements coupled to a toggle linkage, each saidcutting implement includes a forward extending blade with a cutting edgeconfigured to cut through material placed transversely in between saidcutting implements when pressed together with sufficient longitudinalforce created by said roller screw and said electric motor.
 3. The tool,as recited in claim 1, wherein said torque tube and said nut body arelocked together with a key inserted into a keyway formed between saidtorque tube and said nut body.
 4. The tool, as recited in claim 1 wheresaid tool implement is a pair of cutting jaws that open and close whensaid threaded shaft moves axially.
 5. The tool, as recited in claim 1where said tool implement is a pair of spreader jaws that open and closewhen said threaded shaft moves axially.